如果我了解到您需要同时使用cmd和key作为单独的输入，但是用户将输入字符串"cmd key"，则需要分别处理每个字符串，然后一种简单的方法是使用常规std:string运算符（例如

    std::string cmd,key;

    std::cout << "enter command & key: ";
    if (!(std::cin >> cmd >> key)) {    /* read/validate both cmd & key */
        std::cerr << "stream error or use canceled input.\n";
        return 1;
    }

现在，您同时存储了cmd和key，可以使用cmd最初确定要采取的分支，然后根据key选择要采取的行动。例如：

    if (cmd == "kick") {        /* handle cmd "kick" */
        if (key == "ball")
            std::cout << "kicking the ball.\n";
        else if (key == "dog")
            std::cout << "kicking the dog.\n";
        else
            std::cout << "generally kicking the " << key << ".\n";
    }
    else if (cmd == "pick") {   /* handle cmd "pick" */
        if (key == "ball")
            std::cout << "picking the ball.\n";
        else if (key == "dog")
            std::cout << "picking the dog.\n";
        else
            std::cout << "generally picking the " << key << ".\n";
    }
    else    /* otherwise unknown command */
        std::cout << "unknown cmd: " << cmd << ".\n";

（注意：，您始终希望处理用户为每个cmd或key（或两者）输入无效内容的情况

在一个简短的示例中将其放在一起，您可以：

#include <iostream>
#include <string>

int main (void) {

    std::string cmd,key;

    std::cout << "enter command & key: ";
    if (!(std::cin >> cmd >> key)) {    /* read/validate both cmd & key */
        std::cerr << "stream error or use canceled input.\n";
        return 1;
    }

    if (cmd == "kick") {        /* handle cmd "kick" */
        if (key == "ball")
            std::cout << "kicking the ball.\n";
        else if (key == "dog")
            std::cout << "kicking the dog.\n";
        else
            std::cout << "generally kicking the " << key << ".\n";
    }
    else if (cmd == "pick") {   /* handle cmd "pick" */
        if (key == "ball")
            std::cout << "picking the ball.\n";
        else if (key == "dog")
            std::cout << "picking the dog.\n";
        else
            std::cout << "generally picking the " << key << ".\n";
    }
    else    /* otherwise unknown command */
        std::cout << "unknown cmd: " << cmd << ".\n";
}

使用/输出示例

$ ./bin/cmd_select
enter command & key: kick dog
kicking the dog.

使用命令"pick"：

$ ./bin/cmd_select
enter command & key: pick ball
picking the ball.

使用未知命令：

$ ./bin/cmd_select
enter command & key: shoot dog
unknown cmd: shoot.

您当然可以将cmd或key的字符串传递给一个单独的函数，并在该函数中处理您对每个函数的响应，但这只是另一种安排代码以完成相同操作的方式。仔细检查一下，让我知道这是否是您想要的。根据许多修改，我仍然不是100％清楚。